Device for measuring the distance between the optical centers of two or more lenses or optical systems



Dec. 5, 1950 T. G. AULlN 7 2,532,878 DEVICE FOR MEASURING THE DISTANCE BETWEEN THE OPTICAL CENTERS OF TWO OR MORE I LENSES 0R OPTICAL SYSTEMS 2 Sheets-Sheet 1 Filed April 5, 1945 Dec. 5,. 1950 1'. cs. AULIN 2,532,878

- DEVICE FOR MEASURING THE DISTANCE BETWEEN THE OPTICAL CENTERS OF TWO OR MORE LENSES 0R OPTICAL SYSTEMS Filed April 5, 1945 2 sheets-sheet 2 Patented Dec. 5, 1950 DEVIGEFQR MEASURING THE DISTANCE.

BETWEEN THE OETICAL CENTERS OF TWO GR. EIORE LENSES. OETICIAL SYSTEMS Tage Gunner Aulin, Trollhattan, Sweden, as-

signor to J. P. Brandt Aktiebolag, Stockholm, Sweden, a company of Sweden- Appli'cationApril 5, 1945, Serial No. 586,726 in Sweden July 8; 1944 3-Claims. 1-

In writing outa prescription for 'spectacles, the oculist indicates not only the power of the glasses,.but also the distance between the optical centers of the glasses. Moreover, in'certain cases the glasses are to be; at different: levels. The opticalcenter of'thevone glass being; for example, a millimetre or so above thatof thezother glass. Thus, depending on the distance between the patients eyes and possible organicdefects, the opticalicenters of the glasses areto be placed; in a -particular way-in thespectacle-frame. Hithertosuch'mounting has been effected without the use of. measuring instruments, whence the pre scribed'placing has been attainedonlyin excep tional cases. If the deviation istoo. great, howeventheeye-muscles will be-strained, which may giverise to headache, etc.

One'object of the .present inventionis'to eliminate-these disadvantages.- A further. object is to provide a measuringrdevice in which the-distance between the optical centers may. be measured exactly by simple means.

A still further. object of the presentinvention is. to provide a devicefor measuring thedistance or space between optical centers-cf.- twoor. more lenses or optical systems, laterally placed in a holder,. for example,. the distance. between the centers of two. spectacle-glasses mounted. in a. frame.

The invention. is-illustrated on the accompanying drawings by way of. example. Inthe draw-- mg:

Figures 1 and 2 diagrammatically show the pathof. rays ina devicesuitable-for the execution of the invention,

Figure 3. is an elevation, partly insection, .ofone embodiment of. an apparatus according to the invention,

Figure 4 iswaplanview'of parts ofz Figure.3,

Figure 51 isa crosssection on theline.V V in Figure. 4, and- Figure 6v isa. plan view, similar to.Fi'gure- 5., of another embodiment.

With reference toFigures 1 and 2-, I: denotes a source of light illuminating a reticle.- 2 in' the formof a; schematically indicated. cross or. other index. In Figure 1 this cross is .placedinthefocus of a positive-lens 3, and the-parallelpencil of rays proceeding from that lens. is:reiracted by'a lens 4' into the focusof. the latter. If an additional lens 5: (Figure 2.), e. g. a spectacle-glass; is in.- troduced' between thelenses 3 and t; the: 19113.3 must be moved neareir thezreticle 2, SC! that the rays, after. passing the lens. 63,. will again be parallel, In Figure: 2-: the; lens 6;- i's: showrrintrm duced'in .the pencil of rays in such a way that its optical center lies on one side ofthe axis of the projectionsystem. As' shown in this figure, the image 5' of the cross in the reticle 2 Willi-all in the focaliplaneeof the lens 4 on one side of its f0Cl1S;.

In-the focal plane of the lens a is arranged a ruled disc or index disc 5 of any desired appearance, e. g..likewise.in the form of a cross. When the'lens 6. has not been introduced into the pencilof' rays, the image of'the reticle cross- 2 will coincidewith. the cross of the ruled disc 5 (Figure 1). After the introduction of the lens 6, this coincidence will occur only in case the optical center ofthe lens 6 lieson the axis of the projection device. Itis thus. clear that this method enablesza procedure-of: exactly centering the lens 6-inthe path of rays, for the centering is correct whenzthe image of the cross 2 is observed to coincide: with the cross of the disc 5 and'such observation may easily be made by means of an ocular. According to the invention each of the lenses to be measured is first centered in this manner, whereuponthe distance between the paths'ofrays;is:measured by a simple measuring means.

By shifting the lens 3, one can, in'known manher, also find the power of the lens 6.

Figures 3-5 show a device in accordance with the invention; In Figure 3, It denotes a stand provided with a foot I I. At the lower end of'the stand I!) isarranged a projection device oomprisi'ng'a casing l2 with a source of'light t, a reticle 2 and a lens 3' corresponding to the lens 3 'iz1 Fi'gures'l and 2. The reticle 2 can be axially displaced withthe aid of a ring l3, preferably graduated in diopters, and provided with a pin M guided in a spiral groove I6 in-thewall of the casing l2 and adapted-to engage the reticle 2 and carry it in axial direction upon rotation of the ring I35. The adjusted positionof'this ring may be read on the-scale I311 by means of an index At -the upper end Eda of the stand it isplaced a holder l'i' fora lens l-corresponding to the lens 4 in Figures 1 and 2 and a ruled disc or index; disc 5.. (corresponding to the disc 5 in Figure 11) arranged so as to 'he'viewed/ through. an ocular !5, adjustable in known mannerby means ofraiknob. 58: Arranged in the air gap: between the projection device, l, 2, 3 andthe lens l, is a device, shown in greater detail in planview and cross section, respectively, in. Figures 4 and 5. This device consists Of: a supporting table or fastener-ngintended for the reception of a spec;-

tacle-frame G, and provided with a supporting edge or stop 2|. By means of a part 231) the said table 20 is displaceably mounted in a guide 22, which in turn, by means of a cylindrical bolt 23, is displaceably journalled in a sleeve-like part 24 on the stand it.

The supporting table 23 is provided with a projection 25, having a threaded aperture 25 (Figure which cooperates with a screw 27, extending alongside the guide 22 and rotatably journalled in end pieces 23 of the said guide. At one end the screw carries a hand-wheel or knob 29. By turning the said wheel 29, the table 33 can be shifted along the guide 22.

In the bolt 23 there is a threaded groove 38 (Figure 5), in which engages a screw 32, rotatably, but not displaceably journalled in the stand I!) and provided with a hand-wheel or knob 3|. In order to obviate rotation of the bolt 23, it is provided with a guide bar 35, engaging a groove in the boring 2d of the stand :9. Thus, by turning the wheel 3|, the guide 22 and the table 29 can be shifted at right angles to the pencil of rays in the air-gap.

Ihe table 28 has two apertures Li ia, 4% which permit the rays to pass from the projection device I, 2, 3 to the ocular 25 through the spectacle glasses G.

From the lower part of the stand it; a holder 49 extends for a cross-ruled measuring table ll. From the supporting table 39 projects an arm 42, carrying a frame :33, provided with a hair-cross 43a. On the shifting of the table 2% this frame 43 is carried over the measuring table 45.

In using the described device for measuring the distance between optical centers of spectacleglasses G inserted in a frame, the glasses G are placed and clamped on the table 253, so that their lower edges rest against the supporting edge 2! and so that the lenses of the glasses register with the apertures ida, Mb. The table is then shifted, by means of the hand-wheels or knobs 29 and 3!, so that one of the lenses of the eye-glasses is centered in the pencil of rays entering through one of the apertures 44a, 44b in the supporting table say the aperture Add. On the measuring table 4|, preferably cross-ruled in millimetres, as shown at 4 la, the coordinates for the position of the hair-cross eta are then read, whereupon the table 25 is shifted and the other lens of the i eye-glasses is centered in the pencil of rays now entering through the other aperture 44?). By reading the coordinates for the hair-cross in this new position, one can easily find the horizontal distance between the optical centers of the two lenses, as well as the vertical distance between those centers in case of any deviation in a vertical direction.

In order to facilitate measuring in the case of astigmatic lenses, a diaphragm 41 (Figure 3), which, for example, may comprise an apertured plate 45 swivelled on a bolt 46 at the stand, may be introduced between the lens intended for measurement and the holder I! at the upper part of the stand. By the introduction of the said diaphragm, the image of the reticle 2 falling on the ruled plate 5 will be brought out in sharp relief, so that this measurement likewise can be made with great precision.

The measuring table 4| may also be displaceably mounted in a guide 48, 69 (Figure 5) VJith this arrangement it is possible, after the centering of the first lens, to displace the table il until the hair cross Aha registers with the zero point of the table 4| (1. e. the point of intersection of the lines 41b and Mo) whereupon the two distances of the lenses in a horizontal and vertical direction can be found direct, without any computation, by reading the position of the hair-cross 43a after centering of the other lens.

As indicated above, the ring 53 may be provided with a graduated scale 53a, in order to indicate the power of the glass centered in the pencil of rays, in diopters. In order that the glasses shall not irritate the wearer, the error in the distance between them after fitting into the frame must not exceed certain limits.

In order to facilitate the placing of spectacleframes of different sizes, i. e. both for adults and for children, the supporting table 29 may be divided as shown in Figure 6, so that the distance between the openings tide and 4% and between the outer ends of the table can be varied. According to this embodiment the table 26a, which is provided with the aperture 44a, is arranged to slide on guide bars 55 associated with a second table 2513 which is provided with the apertures Mb. Both tables 29a, 2% are displaceable along the screw 2? as a unit. The relative position of the tables, adjusted according to the size of the spectacles to be measured, may be fixed in a suitable manner.

Of course, the invention not limited to measurement of eye-glasses, but can be applied also to other optical devices, for example two camera objectives, fixed relatively to one another. Furthermore, by making the supporting table displaceable also in the direction of the axis of the projection device, the parallelism between the optical axes of the lenses can be controlled.

As astigmatic lenses consist of cylindrical. or sphere-cylindrical glasses, there is no real optical center in them. In such case the position of the cylinder axes is measured with the device in accordance with the invention.

What I claim is:

1. An apparatus for measuring the distance between the optical centers of two spaced and juxtaposed optical systems mounted in a frame comprising in combination a lamp for producing a light beam, a reticle in the path of said light beam, an ocular arrangement containing a hair-crosslike index, a stand in which said lamp, reticle and ocular arrangement are mounted, supporting means for holding the optical systems to be examined, said supporting means being arranged between the reticle and said ocular arrangement and being apertured to enable said light beam to project through each of said optical systems in turn, means for displacing said supporting means in two directions at right angles to each other and to said light beam for the purpose of introducing and centering first one of said optical s5 tems and after displacing said supporting means in one or both of said directions the other of said optical systems in said light beam, measuring means for measuring the displacement of said supporting means in each of said directions, focussing means for focussing an image of said reticle in the plane of said hair-cross said focussing means consisting of a lens arranged between said reticle and said supporting means in the path of said light beam, means for displacing said reticle along the optical axis of said lens and means for measuring the axial displacement of said reticle for the purpose of determining the focus and power in dioptrics of each of said optical systems.

2. An apparatus for measuring the distance between the optical centers of two spaced and juxtaposed optical systems mounted in a frame comprising in combination a lamp for producing a light beam, a reticle in the path of said light beam, an ocular arrangement containing a haircross-like index, a stand in which said lamp, reticle and ocular arrangement are mounted, supporting means for holding the optical systems to be examined, said supporting means being arranged between the reticle and said ocular arrangement and being apertured to enable said light beam to project through each of said optical systems in turn, means for displacing said supporting means in two directions at right angles to each other and to said light beam for the purpose of introducing and centering first one of said optical systems and after displacing said supporting means in one or both of said directions the other of said optical system in said light beam, measurin means for measuring the displacement of said supporting means in each of said directions, iocussing means for focussing an image of said reticle in the plane of said hair-cross, said focussing means consisting of a lens arranged between said reticle and said supporting means in the path of said light beam, means for displacing said reticle along the optical axis of said lens and means for measuring the axial displacement of said reticle for the purpose of determining the focus and power in dioptrics of each of said optical systems, said measuring means comprising a sleeve in which said reticle is arranged to be moved, a rotatable ring outside said sleeve, said ring having a pin thereon connected to said reticle, a spiral groove in the wall of said sleeve, said pin bein movable in said groove, a scale graduated in dioptrics arranged on said ring and an index on said sleeve in register with said scale, said scale having an additional graduation indicating the maximal permissible error in the lateral displacement of the optical axes of said optical systems for different values of their optical strength.

3. An apparatus for measuring the distance between .the optical centers of two spaced and. juxtaposed optical systems mounted in a frame comprising in combination a lamp for producing a light beam, a reticle in the path of said light beam, an ocular arrangement containing a haircross-like index, a stand in which said lamp, reticle and ocular arrangement are mounted, sup- B porting means for holding the optical systems to be examined, said supporting means being arranged between the reticle and said ocular arrangement and being apertured to enable said light beam to project through each of said optical systems in turn, means for displacing said supporting means in two directions at right angles to each other and to said light beam for the purpose of introducing and centering first one of said optical systems and after displacing said supporting means in one or both of said directions the other of said optical systems in said light beam, measuring means for measuring the displacement of said supporting means in each of said directions, focussing means for focussing an image of said reticle in the plane of said haircross said focussin means consisting of a lens arranged between said reticle and said supporting means in the path of said light beam, means for relatively displacing said reticle and said lens alon the optical axis of said lens, and means for measuring said relative axial displacement for the purpose of determining the focus and power in dioptrics of each of said optical systems.

TAGE GUNNAR AULIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 571,781 Mayhew Nov. 24, 1896 703,047 Dirkmann June 24, 1902 1,047,000 De Zeng Dec. 10, 1912 1,242,754 Allen Oct. 9, 1917 1,383,678 Tillyer et a1. July 5, 1921 1,424,941 Pirwirtz Aug. 8, 1922 1,891,052 Ott Dec. 13, 1932 1,959,537 Kuhne May 22, 1934 I 1,974,606 Fassin Sept. 25, 1934 1,981,713 Swenson Nov. 20, 1934 2,081,969 Allen et a1 June 1, 1937 2,387,440 Guellich et al Oct. 23, 1945 FOREIGN PATENTS Number Country Date 231,413 Germany Feb. 21, 1911 

